When your rear tears out your unibody above the subframe...

[DaveAZ]

http://www.turnermotorsport.com/html..._ID=4111225649

Turner motorsport tells you all about it. They sell the factory BMW reinforcement parts that came stock on the E36 M3 which were neglected on the other E36 cars. (see above link.)

You stiffen your suspension and do a few power modifications. You get close to 200hp and eventually every time you hit the throttle you hear a thunk.

The unibody mounting points for the subframe would flex, weaken, and in my case, rip out of the front unibody mounting point of the rear subframe, which is a flat plate with an internally threaded tube welded inside the unibody. The flex of the rear subframe causes the threaded tube and mounting bolt to act as a lever arm at the point where the flat plate is welded to the unibody panel, weakening the surrounding sheet metal. Due to the direction of force of the torque applied by the drivetrain on the subframe, the first mount to rip out is the passenger’s side front mount, followed by the drivers side rear mount.

Turner's page shows you a front mount torn out, but it isn't the car they do their install on. Here you will see why. You need a lot more than the four plates when it is too late...

This is the section of the unibody that I had to replace. It is where the rear subframe mounts to the car, closest to the front of the car. Notice the huge hole where the passenger's side front mount was completely ripped out, requiring this part to be replaced. I think the new one was $95.00.




Here is a close up. The reinforcement plate alone cannot repair this kind of damage.





Here is a look from the other side, which would be hidden from view by the floorpan while installed:


Getting this thing out is no joke. It took me many hours. first I had to use a wire wheel on a drill to get through all the rubberized undercoating. Then there are stich welds every inch or so around the entire thing that I had to chisel out. I had to be careful to not chisel the wrong places or I would be chopping through the underside of the car into the back seat. Did I mention the work required just to get to this?


Being that I don't weld, I had to hire a welder. Don't hire Burnie's welding in Phoenix. He showed up, worked for 20 minutes, dented my trunk lid and hid the dent with a rag, charged me $150.00 and high tailed it out of there. I didn't see the dent until the next day... Grrr. It took me a long time to fing a good welder that was willing to come to me, but I eventually did.


The new unibody piece, installed with the reinforcement plates and sprayed over in rubberized undercoating.


This is what the welding looked like below the back seat before painting over it. You can pass your brake calipers through the fuel pump opening...


And the rear reinforcement plates. The driver's side rear was torn out but was able to be repaired with the reinforcement plate alone.

This was all done two years ago and I just found the pics. I wanted to share my nightmare with others. My downtime ended up being months.
Thanks to Lish for her help and finding Lee, and Lee for his welding. I'm still grateful even though I moved on by three E36 since then...

Oh- I now have Lee weld in the plates BEFORE this happens.

[WTFGERMAN]

wow thats by far the worst one yet, did you have stock subframe bushings?

[DaveAZ]

I never touched the rear of the car prior to this happening aside from M3 springs, thicker anti-sway and some obnoxiously stiff M3 shocks. (Don't buy Monroe.)

It was a 1992 325IS. With the removed unibody part and the new one side-by-side there was a blatant difference in their design.

The 1992 had the cup-like thing you could see in the pictures above. The new one didn't. It was a few years ago so I don't remember much else and I didn't photograph that stuff. I'm lucky I took these pictures and got possession of them with a borrowed camera at the time.

[atlantisvip]

Damn !

[EURO M3 CSL]

damn.. speaking of which i got to do all the reinforcement on my dads 92'325i now before this happens

[atlantisvip]

I never touched the rear of the car prior to this happening aside from M3 springs, thicker anti-sway and some obnoxiously stiff M3 shocks. (Don't buy Monroe.)

It was a 1992 325IS. With the removed unibody part and the new one side-by-side there was a blatant difference in their design.

The 1992 had the cup-like thing you could see in the pictures above. The new one didn't. It was a few years ago so I don't remember much else and I didn't photograph that stuff. I'm lucky I took these pictures and got possession of them with a borrowed camera at the time.

Dammit bro.. You got me all panicky. I have a 92 with monroes.. This is gonna be a bitch.

[slim17265]

doing doughnuts in the parking lot? eh

[DaveAZ]

doing doughnuts in the parking lot? eh

No, but I did a lot of nailing it off the line. The final 'Bang' happened while powersliding a turn, located 1/2 mile from my house after a long high-speed highway drive. A Police officer pulld me over after the turn and while he was running my license he asked me to get out of my car to look at my rear tires. There was smoke coming off of them... No ticket that day.

[E36MikeFL]

bump of a lil bit of a old thread, but do you remember if your new unibody panels came with the internally threaded tube or whatever welded inside? or did you have to have them welded in, in between the new panels and floor pan? mine looks about like yours but front and rear

[DaveAZ]

The unibody panel came ready to install equipped with the threaded parts to accept the front of the differential carrier. I welded the M3 renforcements onto it prior to installing it. good luck!

[BMWMPow3r]

nice pics.

[Rhyspaul]

Hey I know this threads pretty old but do you happen to know what part number the unibody piece was or where you got it from. My cars been off the streets for over a month and I'd like to get it done.

[DaveAZ]

41118174049 from the dealer.

[Rhyspaul]

Awesome! thanks and just wondering, did it come with the female threads or did you use the old ones?

[DaveAZ]

It's all there. Just weld the M3 plates on it, then it to the car (after you gently chisel yours off.) Add the rear plates to the car, too.

[Rhyspaul]

hey dave, I finished the rebuild back in december but sadly it wasn't enough. The clunk came back in about a month and i cant seem to locate the problem. I welded up the unibody piece just like you said, I kinda puzzle pieced the chassis back together on the rear left mount then welded the plates up nice, I even took a hole saw to the trunk so i could open up and weld the top part of the thread to a washer and welded the washer onto the chassis. I've looked under my car and checked the mounts like i did when the problem first started and it all looks locked in. there's no cracks in the sealant i used and not a sign of it tearing from the car. I did find that the knock felt like it was hitting the back seat, but i took the hole saw to where the right front mount was and nothing seemed to be moving. I think it might be coming from the unibody but I'm not sure how or where. I'll try to get some pics up of the repair soon.

[Pdwight]

Did you ever find it....I know this is a year old...but I have developed a bump

[somebody5788]

Most BMW's have a thud when you shift into gear. Typically bad diff mounts or DS support bearing. There are other causes too.

[downandout]

I just did the same replacement it took about 50hrs of work.
image.jpg
This was the reason.
image.jpg
image.jpg
You can drill out 80% of the spot welds from the top, you just have to grind out the ones on the sides from underneath. But the real hard part is grinding out the stitch welds on the frame rails, as it is sandwiched in under them and the floor.
image.jpg
Old one Removed.
image.jpg
You can see how on the early e36 the cone shaped mounts that rip out from the top the only way to fix that would be to cut the floor under the rear seat to access the top. I felt it would be a better repair to just replace it.

[downandout]

image.jpgimage.jpgimage.jpg
Plug welded from the top and bottom.
the new one does not have the cone to hold in the threaded shaft. it's just the shaft spot welded to the bottom instead of just being sandwiched and stitch welded to the cone top.
I hate to say it, but it's probably easier to just swap your drive train to another e36, than replacing the subframe mountain points.

[faisduvtt]

Dave - looks like these images have expired. Any way you can send me the images or update this post? I crashed our 1994 325i LeMons racer hard this weekend and broke the 2 subframe bolts so we're faced with this daunting repair now.

http://www.turnermotorsport.com/html..._ID=4111225649

Turner motorsport tells you all about it. They sell the factory BMW reinforcement parts that came stock on the E36 M3 which were neglected on the other E36 cars. (see above link.)

You stiffen your suspension and do a few power modifications. You get close to 200hp and eventually every time you hit the throttle you hear a thunk.

The unibody mounting points for the subframe would flex, weaken, and in my case, rip out of the front unibody mounting point of the rear subframe, which is a flat plate with an internally threaded tube welded inside the unibody. The flex of the rear subframe causes the threaded tube and mounting bolt to act as a lever arm at the point where the flat plate is welded to the unibody panel, weakening the surrounding sheet metal. Due to the direction of force of the torque applied by the drivetrain on the subframe, the first mount to rip out is the passenger’s side front mount, followed by the drivers side rear mount.

Turner's page shows you a front mount torn out, but it isn't the car they do their install on. Here you will see why. You need a lot more than the four plates when it is too late...

This is the section of the unibody that I had to replace. It is where the rear subframe mounts to the car, closest to the front of the car. Notice the huge hole where the passenger's side front mount was completely ripped out, requiring this part to be replaced. I think the new one was $95.00.




Here is a close up. The reinforcement plate alone cannot repair this kind of damage.





Here is a look from the other side, which would be hidden from view by the floorpan while installed:


Getting this thing out is no joke. It took me many hours. first I had to use a wire wheel on a drill to get through all the rubberized undercoating. Then there are stich welds every inch or so around the entire thing that I had to chisel out. I had to be careful to not chisel the wrong places or I would be chopping through the underside of the car into the back seat. Did I mention the work required just to get to this?


Being that I don't weld, I had to hire a welder. Don't hire Burnie's welding in Phoenix. He showed up, worked for 20 minutes, dented my trunk lid and hid the dent with a rag, charged me $150.00 and high tailed it out of there. I didn't see the dent until the next day... Grrr. It took me a long time to fing a good welder that was willing to come to me, but I eventually did.


The new unibody piece, installed with the reinforcement plates and sprayed over in rubberized undercoating.


This is what the welding looked like below the back seat before painting over it. You can pass your brake calipers through the fuel pump opening...


And the rear reinforcement plates. The driver's side rear was torn out but was able to be repaired with the reinforcement plate alone.

This was all done two years ago and I just found the pics. I wanted to share my nightmare with others. My downtime ended up being months.
Thanks to Lish for her help and finding Lee, and Lee for his welding. I'm still grateful even though I moved on by three E36 since then...

Oh- I now have Lee weld in the plates BEFORE this happens.

[Kapoosta]

Dave - looks like these images have expired. Any way you can send me the images or update this post? I crashed our 1994 325i LeMons racer hard this weekend and broke the 2 subframe bolts so we're faced with this daunting repair now.

Try using this fix for photobucket images: https://www.bimmerforums.com/forum/s...ht=photobucket
I can see all of the pictures fine with this plugin enabled in Chrome.

[TipsyMcStagger]

http://www.turnermotorsport.com/html..._ID=4111225649

Turner motorsport tells you all about it. They sell the factory BMW reinforcement parts that came stock on the E36 M3 which were neglected on the other E36 cars. (see above link.)

You stiffen your suspension and do a few power modifications. You get close to 200hp and eventually every time you hit the throttle you hear a thunk.

The unibody mounting points for the subframe would flex, weaken, and in my case, rip out of the front unibody mounting point of the rear subframe, which is a flat plate with an internally threaded tube welded inside the unibody. The flex of the rear subframe causes the threaded tube and mounting bolt to act as a lever arm at the point where the flat plate is welded to the unibody panel, weakening the surrounding sheet metal. Due to the direction of force of the torque applied by the drivetrain on the subframe, the first mount to rip out is the passenger’s side front mount, followed by the drivers side rear mount.

Turner's page shows you a front mount torn out, but it isn't the car they do their install on. Here you will see why. You need a lot more than the four plates when it is too late...

This is the section of the unibody that I had to replace. It is where the rear subframe mounts to the car, closest to the front of the car. Notice the huge hole where the passenger's side front mount was completely ripped out, requiring this part to be replaced. I think the new one was $95.00.




Here is a close up. The reinforcement plate alone cannot repair this kind of damage.


Here is a look from the other side, which would be hidden from view by the floorpan while installed:


Getting this thing out is no joke. It took me many hours. first I had to use a wire wheel on a drill to get through all the rubberized undercoating. Then there are stich welds every inch or so around the entire thing that I had to chisel out. I had to be careful to not chisel the wrong places or I would be chopping through the underside of the car into the back seat. Did I mention the work required just to get to this?



Being that I don't weld, I had to hire a welder. Don't hire Burnie's welding in Phoenix. He showed up, worked for 20 minutes, dented my trunk lid and hid the dent with a rag, charged me $150.00 and high tailed it out of there. I didn't see the dent until the next day... Grrr. It took me a long time to fing a good welder that was willing to come to me, but I eventually did.

[TipsyMcStagger]

The new unibody piece, installed with the reinforcement plates and sprayed over in rubberized undercoating.




This is what the welding looked like below the back seat before painting over it. You can pass your brake calipers through the fuel pump opening...



And the rear reinforcement plates. The driver's side rear was torn out but was able to be repaired with the reinforcement plate alone.

This was all done two years ago and I just found the pics. I wanted to share my nightmare with others. My downtime ended up being months.
Thanks to Lish for her help and finding Lee, and Lee for his welding. I'm still grateful even though I moved on by three E36 since then...

Oh- I now have Lee weld in the plates BEFORE this happens.

[apex17]

Where can you buy a new e36 racp (rear axle carrier panel) to weld in?

Thanks,